1. Field of the Invention
This invention relates generally to the field of environmental remediation of stormwater. More specifically, this invention relates to an improved modular filtration system for a stormwater system.
2. Description of the Related Technology
Stormwater that is created by storm runoff in heavily developed areas is typically channeled into storm drainage systems that eventually drain into nearby streams, creeks, rivers or other bodies of water. For purposes of this document, stormwater includes not only storm runoff, but other sources of wastewater such as rinse water and melting snow and ice.
Paved surfaces that bear automobile traffic typically become coated with significant pollutants such as heavy metals and volatile organic compounds, both under normal traffic conditions and in particular when motor vehicle accidents occur. When normal rain or snowfall occurs, these pollutants tend to be swept away with the runoff stormwater and eventually lead to contamination of the bodies of water that eventually receive them. Such contamination has become a significant environmental issue in many areas. In addition, a significant amount of sediment and debris such as bottles and cans tends to be swept away by stormwater runoff. Some of the debris is heavier than water, and some of it has the tendency to float. Stormwater filtering systems have to be able to effectively filter both types of debris, in both ordinary and elevated flow conditions.
Depending on the location of a stormwater system inlet, the primary environmental concern may be pollutants or it may be sedimentation and larger debris.
Systems exist for filtering stormwater runoff that are effective to some extent in removing debris from stormwater and in removing certain other pollutants, such as hydrocarbons. For example, U.S. Pat. No. 6,080,307 discloses a storm drain insert that contains one basket for the collection of debris as well as a canister that contains a hydrophobic, compliant, oil-absorbent copolymer material that is said to be effective in removing oil from the stormwater. Additional systems for removing pollutants such as heavy metals from stormwater have been commercialized by Fabco Industries Inc., the assignee of this application.
The removal of sedimentation and larger debris from stormwater requires a system that is simple to install and to service, since the collected sedimentation and debris will have to periodically be removed from the system. Water treatment media such as filtration media will also have to be periodically inspected and replaced.
In any type of water treatment system, there is a trade-off between the amount of stormwater that the system can effectively process and the efficiency of the water treatment. In other words, for a given system, the greater the amount of stormwater to be processed, the less effective the treatment can be. Accordingly, it is advantageous to be able to design a system that is scalable for the anticipated flow rates in order to optimize water treatment efficiency and longevity of the system.
A need exists for an improved system and process for processing sediment and debris laden stormwater that can be optimized for anticipated conditions, that is effective under all conditions, that is suitable for filtering all kinds of debris, and that is moreover inexpensive to deploy and cost-effective to service.